530 Contributions to Invertebrate Palaeontology. 



pears to have been destitute of strong surface markings. It measures 

 about seven inches in length by nearly four inches in transverse 

 diameter at the widest part, which is near the lower part of the 

 outer chamber. The lower end is imperfect, and measures one and 

 a half inches in transverse diameter. It is with some hesitation 

 that I place the species under the genus Gomphoceras, owing to the 

 strong curvature of the shell and the structure of the aperture, 

 which is reversed in its relation to the curvature of the shell as 

 compared with most species of the genus; the widest portion being 

 on the inside curvature, instead of on the outer side. The general 

 triangular or trilobed form of the aperture, together with the greater 

 lateral diameter, would seem to overbalance the fact of the curva- 

 ture. 



Formation and Locality. — In limestone of the Upper Helderberg 

 group, at Smith and Price's quarries, near Columbus, Ohio. Named 

 in honor of Mr. E. Hyatt, from whose collection it was obtained. 



tromplioceras amphora. 



Plate VII, fig. 9. 



Gomphoceras amphora Whitf., Aim. N. Y. Acad. Sci., March, 1882, p. 207. 



Shell of large size, elongate-ovate or short sub-fusiform, somewhat rapidly 

 expanding from below upward to within a short distance of the base of the 

 outer chamber ; from which point it again contracts more rapidly to about 

 one-half the heiglit of the outer chamber, and is then drawn out into a narrow 

 neck, resembling the neck of a bottle, of a width but little exceeding one-tliird 

 of the diameter of the larger jiortion of the shell. Aperture not distinctly 

 traced, but on the side figured, there is an appearance of a deep, rather narrow 

 sinus, extending nearly one-half the depth of the outer chamber. The shell 

 bears the appearance, also, of having been curved, as indicated ^principally by 

 the obliquity of the septa, which are numerous, rather deeply concave, and 

 arranged at a distance of about one-fourth of an inch in the largest part of the 

 specimen, and decreasing in distance below and above ; while near the base of 

 the outer chamber there are about six septa closely crowded togetlier. Position 

 of the siphuncle not determined. 



The species resembles G. eximium Hall, of the same formation, 

 in the lower part of its length, although more rapidly expanding, 

 but in the upper part, and especially near the aperture, differs en- 

 tirely from any other species known. 



Formation and Locality. — In the limestone of the Upper Helder- 

 berg group, in Marion Co., Ohio. Collection of Columbia College, 

 New York. 



